1. Field of the Invention
This invention relates generally to a current limited strobe charging circuit and, more particularly, to a strobe charging circuit in which the current is limited during the time required to reform the primary storage capacitor without materially affecting the current flow and time required to subsequently recharge the storage capacitor after it has been reformed.
2. Description of the Prior Art
Electronic flash or strobe devices comprising a flash discharge tube through which the charge from a primary storage capacitor may be discharged to provide an illuminating flash of light are conventional and well known to the art. Such storage capacitors may be charged by a variety of means in which the oscillating output of a power supply is generally stepped up to charge the capacitor at the requisite voltage required to provide the illuminating flash of light upon the discharge thereof through the flash discharge tube. Such storage capacitors if not frequently recharged develop high leakage currents after long periods of non-use and thus must be reformed so as to reduce the leakage current to a value at which energy can then be stored in the capacitor. The initial reforming of the capacitor can result in an excessive current drain as a result of the high leakage current thereby overloading and potentially damaging other components in the electronic flash charging circuit. In order to avoid such a dangerous overloading condition, some means of controlling the current must be provided which limits the current flow during the time required to reform the primary storage capacitor while not limiting the current flow during the time that the primary storage capacitor is recharged subsequent to its reforming. Thus, as is readily apparent, the current control must be variable so as to accommodate the variation in current drain presented by the primary storage capacitor during the time in which it is reformed and the succeeding time in which it is recharged.
Simple electronic flash charging circuits embodying voltage doubling circuits are well known in the art and provide a convenient, economical and simple circuit for charging a flash storage capacitor from an ordinary 115 volt AC line source. Such strobe charging circuits embodying voltage doublers, however, are particularly susceptible to the high current drains presented by leaky storage capacitors that must be reformed and inclusion of a complex current control circuit would substantially add to the complexity and cost of what is otherwise a simple and economical strobe charging circuit.
Therefore, it is a primary object of this invention to provide a simple and economical means for controlling the current flow in a flash charging circuit susceptible to high current drains encountered when storage capacitors must be initially reformed.
It is a further object of this invention to provide a simple and economic means for controlling the current flow to an electronic flash charging circuit of the type in which a voltage doubler circuit is utilized to limit the current flow during the time required to reform a storage capacitor without materially affecting the current flow and time required to subsequently charge the storage capacitor after it is reformed.
Other objects of the invention will in part be obvious and will in part appear hereinafter.